Of kittens and teacups and love by Ren. XMFC story in which Erik is Charles' roommate, and Charles adopts more and more kittens. The story also inspired cat-related fanart. Although XMFC fandom has its fair share of cat fanworks, no cats appear in the film. (2011)

Time in a Bottle by astolat, a Stargate Atlantis story that includes an original cat character named Fermi. Fermi is presented as a virtual copy of Rodney McKay's first cat and is presumably inspired by the fact that Rodney is canonically a cat person; he is briefly shown giving away an unnamed cat in the pilot episode. (2005)

Gods and Monsters by silverkit, Supernatural fic written from outside POV in which Sam and Dean are transformed into cats who temporarily seek shelter with some humans (but Sam still has visions and they're still on the case). (2007)

Humane Society by smilebackwards. XMFC story in which Erik is temporarily transformed into a kitten. "Once Erik finally allows himself to decide that Charles is pretty much the best thing since sliced bread, he spends the next week being incredibly bitter that he's Charles' cat and not his boyfriend."Example fanart based on the story. (2011)